Gold alloy



i UNITED STATES Patented July 11, 1933 i PATENT OFFICE i 7 Louis LENrAri'r, or rams, FRANCE, essrenon. T CARTIER, SOGIETE ANONYMLE, or

PARIS, FRANCE, A COMPANY OF-FRANCE GOLD ALLOY cording to the fineness of the alloy that isdesired; 4

The remainder consists of silver and copper, and cobalt which must always be employed together according to the present invention. The ratio of the amount of copper to the amount of silver will preferably average from 1.2 to 1.5 according to the desired shade of the alloy.

The ratios of the-quantities of chromium and cobalt to the whole alloy will be 0.5 to 4 per centfor the cobalt and 0.5 to 1 per cent for the chromium according to the hardening efiect that is to be obtained. 1

'The hardness of the alloy immediately after casting is' 168 Brinnell.

By way of example,-1' may indicate that for an alloy containing 7 5 per cent of gold,

13.5 per cent of copper, 10 per cent of silver,

- 1 per cent of cobalt, 0.5 per cent of chromium, tempering lowers-said hardness to 140 and a heating at 200 C. for 4 hours brings it to 217.

L For an alloy containing 65 per cent of gold,

19.5 per cent of copper, 14 per cent, of silver,

1 per cent of cobalt, 0.5 per cent of chromium the hardness in the raw state is 174, after tempering 147 and after annealing 260.

These alloys never-have any micro fissura- .state, are easily welded and their hardness I malres'it possible to give them a remarkable Said alloys are well adapted to the manu'- 40 facture of ]8WelS, boxes or plates either for domestic or for laboratory purposes. a They are especially well suited to the manufacture of gold cutlery.

The 'micrographic study of said alloys 4 shows a structure having a very fine grain, after tempering and annealing, which ensures a perfect homogeneity.

p The advantages of said gold alloys are the .following: 1. It is possible to harden the alloy at will,

and a certain amount of chromium 13.5 l 1 t trons. -They are easily rolled in the coldcopper per cent S1 0 per cen j foregoing specification.

1T0 Drawing. 'Application and July 18, 1931, Serial No. 551,793, aim in France March 10,1931.

which allows to shape an article while the metal is soft, and then to give it the required hardness after treatment by annealing. The low temperature at which said annealing takes place makes it possible to avoid any injury of thearticle.

2. These alloys forge as well in the hot as in the cold state, which is generally not possible with ordinary gold alloys.

3. These alloys do'not cause any alteration in the shade of the enamels.

4. They can be given an especially high polish owing to the hardness that is imparted to them by annealing, which hardness is much greater than that of other commercial gold alloys.

It should be well understood that the ez'zamples that have been indicated can be modi- -fied without departing from the spirit of the invention as comprehended within the scope of the appended claims.

What I claim is: 1. An alloy containing:

Per cent Gold -65 I5 Copper 13.5-19.5 1 Silver 10-145 Cobalt 1 Chromium 0. 5

balt,1 per cent and chromium, 0.5 per cent.

3. An alloy containing: gold, 65 per cent, copper, 19.5 percent, silver, 14 per cent, cobalt 1 per cent and chromium 0.5 per cent.

'In'test-imony whereof, I have signed the LOUIS LENFANT. 

